Merck Manual

Please confirm that you are a health care professional

honeypot link

Pneumothorax (Tension)


Thomas G. Weiser

, MD, MPH, Stanford University School of Medicine

Last full review/revision May 2020| Content last modified May 2020
Click here for Patient Education
Topic Resources

Tension pneumothorax is accumulation of air in the pleural space under pressure, compressing the lungs and decreasing venous return to the heart.

Tension pneumothorax develops when a lung or chest wall injury is such that it allows air into the pleural space but not out of it (a one-way valve). As a result, air accumulates and compresses the lung, eventually shifting the mediastinum, compressing the contralateral lung, and increasing intrathoracic pressure enough to decrease venous return to the heart, causing shock. These effects can develop rapidly, particularly in patients undergoing positive pressure ventilation.

Causes include mechanical ventilation (most commonly) and simple (uncomplicated) pneumothorax with lung injury that fails to seal following penetrating or blunt chest trauma or failed central venous cannulation.

Symptoms and Signs of Tension Pneumothorax

Symptoms and signs initially are those of simple pneumothorax. As intrathoracic pressure increases, patients develop hypotension, tracheal deviation, and neck vein distention. The affected hemithorax is hyperresonant to percussion and often feels somewhat distended, tense, and poorly compressible to palpation.

Diagnosis of Tension Pneumothorax

  • Clinical evaluation

Tension pneumothorax should be diagnosed by clinical findings. Treatment should not be delayed pending radiographic confirmation. Although cardiac tamponade also can cause hypotension, neck vein distention, and sometimes respiratory distress, tension pneumothorax can be differentiated clinically by its unilateral absence of breath sounds and hyperresonance to percussion.

Pearls & Pitfalls

  • Tension pneumothorax should be diagnosed at the bedside based on clinical findings and treated immediately with needle decompression and/or tube thoracostomy.

Treatment of Tension Pneumothorax

  • Needle decompression followed by tube thoracostomy

Treatment of tension pneumothorax is immediate needle decompression by inserting a large-bore (eg, 14- or 16-gauge) needle into the 2nd intercostal space in the midclavicular line. Air will usually gush out. Because needle decompression causes a simple pneumothorax, tube thoracostomy should be done immediately thereafter.

Click here for Patient Education
NOTE: This is the Professional Version. CONSUMERS: Click here for the Consumer Version
Professionals also read

Test your knowledge

A male patient who is homeless is brought to the emergency department (ED) after he was found disoriented and confused on the street during winter. Physical examination on route to the ED showed unreactive pupils and bradycardia. Currently, the patient is irritable and his speech is slurred. Which of the following is the most appropriate initial step in diagnosis? 
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID